Electrochromic devices

ABSTRACT

This invention contemplates integrating laser scribing/patterning the component layers of electrochromic devices by directly removing (ablating) the material of the component layers. To minimize redeposition of laser ablated material and particulate formation on device surfaces a number of approaches may be used: (1) ablated material generated by the focused laser patterning may be removed by vacuum suction and/or application of an inert gas jet in the vicinity of the laser ablation of device material; (2) spatial separation of the edges of layers and patterning of lower layers prior to deposition of upper layers; and (3) the laser patterning step may be performed by a laser beam focused directly on the deposited layers from above, by a laser beam directed through the transparent substrate, or by a combination of both.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.12/134,437, filed Jun. 6, 2008, now U.S. Pat. No. 8,168,265, which isincorporated by reference herein in its entirety.

FIELD OF THE INVENTION

The present invention relates generally to electrochromic devices, andmore particularly to a method for fabricating electrochromic devicesincluding laser patterning/scribing.

BACKGROUND OF THE INVENTION

Electrochromic devices are devices that change light (and heat)transmission properties in response to voltage applied across thedevice. Electrochromic devices can be fabricated which electricallyswitch between transparent and translucent states (where the transmittedlight is colored). Furthermore, certain transition metal hydrideelectrochromic devices can be fabricated which switch betweentransparent and reflective states. Electrochromic devices areincorporated in a range of products, including architectural windows,rear-view mirrors, and protective glass for museum display cases. Whenthey are incorporated in architectural windows there is a need for theelectrochromic devices to have a guaranteed lifetime of at least tenyears and preferably thirty years or more. However, exposure of theelectrochromic devices to atmospheric oxygen and water can degrade theperformance of the devices and reduce the lifetime of the devices.Therefore, there is a need for electrochromic devices designed towithstand the deleterious effects of ambient oxidants.

Architectural windows are generally in the form of an insulated glassunit (IGU). An IGU comprises two spaced apart panes of glass sealedalong all four edges. The interior volume is filled with an inert gas,such as argon, so as to provide thermal insulation. When anelectrochromic device is incorporated into the IGU it is fabricated onthe exterior glass pane (the outdoors facing pane) and is positioned onthe interior facing surface thereof. The inert environment within theIGU does not affect the performance of the electrochromic device.However, in case of a failure of the seal of the IGU, for example, thereis still a need to protect the electrochromic devices against ambientoxidants.

A prior art electrochromic device 100 is represented in FIG. 1. See U.S.Pat. No. 5,995,271 to Zieba et al. The device 100 comprises a glasssubstrate 110, lower transparent conductive oxide (TCO) layer 120, acathode 130, a solid electrolyte 140, a counter electrode 150, upper TCOlayer 160, a protective coating 170, a first electrical contact 180 (tothe lower TCO layer 120), and a second electrical contact 190 (to theupper TCO layer 160). Furthermore, there may be a diffusion barrierlayer (not shown) between the glass substrate 110 and the lower TCOlayer 120, to reduce the diffusion of ions from the glass substrate intothe TCO layer, and vice versa. Note that the component layers are notdrawn to scale in the electrochromic device shown in FIG. 1. Forexample, a typical glass substrate is of the order of a millimeter thickand a typical electrochromic device covers the fully exposed area of thearchitectural glass, or rear-view mirror, for example. Other substratematerials may be used, for example plastics such as polyimide (PI),polyethylene terephthalate (PET) and polyethylene naphthalate (PEN).Typical component layer thicknesses are given in the table below:

Component Layer Thickness (microns) lower TCO layer 0.1 to 1.0 cathode0.1 to 1.0 solid electrolyte 0.005 to 0.5 counter electrode 0.1 to 1.0upper TCO layer 0.1 to 1.0 diffusion barrier layer 0.1 to 1.0

Switching from a transparent to a colored state, for example, occurswhen ions (such as lithium or hydrogen ions) are driven from the counterelectrode 150, through the (non electrically conductive) solidelectrolyte 140, to the cathode 130. The counter electrode 150 is an ionstorage film, and the cathode 130 is electrochromic—providing thedesired change in light transmission properties. It is also possible forthe counter electrode 150 to function as the electrochromic layer ifthis layer undergoes an “anodic coloration,” where the layer changesfrom transparent to colored with de-intercalation of the ion. In thiscase, the cathode becomes the counter electrode. One can also creategreater contrast by combining the effects of both electrodes. A moredetailed discussion of the functioning of electrochromic devices isfound in Granquvist, C.-G., Nature Materials, v5, n2, February 2006, p89-90. For the device to function properly, the lower TCO layer 120 andthe cathode 130 must be electrically isolated from the counter electrode150 and upper TCO layer 160. Electrical contact to external drivercircuits is made through the first and second electrical contacts 180and 190.

As is clear from FIG. 1, the device 100 requires patterning of the fiveactive device layers 120-160. This patterning can be done usingconventional physical/shadow mask-based lithography techniques. The useof traditional lithography techniques with physical masks leads to manydisadvantages, especially related to high volume manufacturing (HVM).For example, the use of physical masks: (1) adds a significant capitalinvestment requirement for HVM and large area scaling; (2) increases thecost of ownership (consumable mask cost, cleaning, chemicals, etc.); (3)decreases the throughput because of alignment requirements; and (4)results in a yield loss, since the masks are prone to flaws whichtranslate to defects in the electrochromic devices, such as colorcenters and pinholes in protective layers. The presence of pinholes inprotective layers will eventually lead to failure of the electrochromicdevices due to oxidants reaching the active layers of the devices. Thisoccurs for electrochromic devices sealed in IGUs when the IGU sealbecomes compromised and atmospheric oxidants leak into the unit. Thedesired device lifetimes of tens of years cannot be achieved withpinhole defects in the protective layers. In HVM processes, the use ofphysical masks (ubiquitous for traditional and current state-of-the-artelectrochromic device fabrication technologies) will contribute tohigher complexity and higher cost in manufacturing. The complexity andcost result from the requirement to fabricate very accurate masks andthe need to use (automated) management systems for mask alignment andregeneration. Such cost and complexity can be inferred from well knownphotolithography processes used in the silicon-based integrated circuitindustry. In addition, the higher cost results from the need formaintaining the masks as well as from throughput limitations by theadded alignment steps. The adaptation becomes increasingly moredifficult and costly as the manufacturing is scaled to larger areasubstrates. Moreover, the scaling (to larger substrates) itself can belimited because of the limited availability and capability of thephysical masks. This is particularly critical for the architecturalwindow applications, where innumerable shapes and sizes are required.Therefore, there is a need for cost effective, flexible and high volumemanufacturing compatible fabrication methods for electrochromic devices.Furthermore, due to the yield issues associated with mask-basedlithography fabrication steps, there remains a need for improved methodsfor patterning the numerous component layers of electrochromic devices.

Patterning of the five active device layers 120-160, shown in FIG. 1,can be done using laser scribing techniques. See U.S. Pat. No. 5,724,175to Hichwa et al. However, the laser scribing method of Hichwa et al.results in contamination of the exposed edges of the activeelectrochromic layers due to redeposition during laser ablation ofmaterial on the walls of the trench being cut. This contamination canimpair the performance of the electrochromic device. Furthermore,particulates are generated during laser ablation and these particles aredeposited on the surface of the device. When the protective coating isapplied, the presence of particulates on the surface can lead topinholes in the coating. Pinholes in the protective coating can resultin exposure of the device to oxidants from the ambient, and ultimatelyto premature device failure. There is a need for laser scribingprocesses which do not impair electrochromic device performance.

In conclusion, there is a need for improved patterning processes forelectrochromic devices and a need for improvement in the integration ofpatterning processes into device fabrication for electrochromic devices.

SUMMARY OF THE INVENTION

The concepts and methods of the invention allow the cost and complexityof electrochromic device high volume manufacturing to be reduced byeliminating and/or minimizing the use of conventional masks to enhancemanufacturability of the products at high volume and throughput and onlarge area substrates. This can significantly reduce the cost for broadmarket applicability as well as provide yield improvements. This isachieved while ensuring the active layers of the device are protectedover the long term from environmental oxidants. According to aspects ofthe invention, these and other advantages are achieved with the use oflaser patterning/scribing to meet certain or all of the patterningrequirements, while integrating the laser scribing so as to ensure theactive layers of the device are protected to ensure long termreliability. It is envisaged that the laser is used to pattern thecomponent layers of electrochromic devices by directly removing(ablating) the material of the component layers. As such, this inventioncontemplates laser patterning integrated into the manufacturing processas deemed appropriate and necessary for electrochromic devicemanufacturability, yield, functionality, and long term reliability. Thisincludes a manufacturing method for an electrochromic device comprisingthe following steps: (1) depositing a first transparent conductive layerfollowed by a cathode on a transparent substrate; (2) patterning thecathode; (3) depositing an electrolyte layer, followed by a counterelectrode layer, followed by a second transparent conductive layer; (4)focused laser patterning the electrolyte, counter electrode andtransparent conductive layers; (5) depositing a diffusion barrier; and(6) forming separate electrical contacts to the first transparentconductive layer and the second transparent conductive layer. Thepatterning step in (2) may also be a focused laser patterning process.In this method laser patterning of the first transparent conductivelayer and the cathode layer occurs before deposition and laserpatterning of the remaining layers, thus eliminating any contaminationof the remaining layers due to redeposition of the transparentconductive material and cathode material on their surfaces. Furthermore,during focused laser patterning, ablated material generated by thefocused laser patterning may be removed. In general, redeposition ofablated material and particulate contamination due to laser ablation canbe minimized by using tactics such as spatially separating edges ofupper and lower layers and/or patterning of lower layers prior todeposition of upper layers.

Another manufacturing method for an electrochromic device includes thefollowing steps: (1) sequentially depositing layers corresponding to anelectrochromic device on a substrate, a first layer being a firsttransparent conductive layer and a last layer being a second transparentconductive layer; (2) focused laser patterning the layers, where thepatterning isolates separate electrochromic devices on the substrate andexposes the surface of a first transparent conductive layer for makingelectrical contact; (3) during the focused laser patterning, removingablated material generated by the focused laser patterning; (4)depositing a diffusion barrier; and (5) forming separate electricalcontacts to the first transparent conductive layer and the secondtransparent conductive layer.

In the above methods, as material is ablated by the laser patterningprocess it may be removed by: vacuum suction in very close proximity tothe site of laser ablation; and/or a jet of inert gas directed acrossthe surface of the device in the vicinity of laser ablation. Inaddition, a (cooled) surface can be strategically placed near the focalpoint of the ablating region (e.g., where the suction or gas jet isplaced) to capture (via deposition) the ablated materials. Furthermore,the laser patterning step may be performed by a laser beam focuseddirectly on the deposited layers from above, by a laser beam directedthrough the transparent substrate, or by a combination of both.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other aspects and features of the present invention willbecome apparent to those ordinarily skilled in the art upon review ofthe following description of specific embodiments of the invention inconjunction with the accompanying figures, wherein:

FIG. 1 illustrates a prior art electrochromic device;

FIGS. 2A to 2E illustrate an example electrochromic device fabricationprocess according to aspects of the invention;

FIGS. 3A to 3E illustrate additional aspects of an exampleelectrochromic device fabrication process of the invention;

FIG. 4 illustrates examples of laser scribing and ablated materialremoval process steps in the fabrication of electrochromic devicesaccording to aspects of the invention;

FIG. 5 illustrates an additional example of laser scribing and ablatedmaterial removal process steps in the fabrication of electrochromicdevices according to aspects of the invention; and

FIG. 6 illustrates a further example of laser scribing and ablatedmaterial removal process steps in the fabrication of electrochromicdevices according to aspects of the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention will now be described in detail with reference tothe drawings, which are provided as illustrative examples of theinvention so as to enable those skilled in the art to practice theinvention. Notably, the figures and examples below are not meant tolimit the scope of the present invention to a single embodiment, butother embodiments are possible by way of interchange of some or all ofthe described or illustrated elements. Moreover, where certain elementsof the present invention can be partially or fully implemented usingknown components, only those portions of such known components that arenecessary for an understanding of the present invention will bedescribed, and detailed descriptions of other portions of such knowncomponents will be omitted so as not to obscure the invention. In thepresent specification, an embodiment showing a singular component shouldnot be considered limiting; rather, the invention is intended toencompass other embodiments including a plurality of the same component,and vice-versa, unless explicitly stated otherwise herein. Moreover,applicants do not intend for any term in the specification or claims tobe ascribed an uncommon or special meaning unless explicitly set forthas such. Further, the present invention encompasses present and futureknown equivalents to the known components referred to herein by way ofillustration.

In general, the present invention contemplates an alternative method ofpatterning certain or all layers in an electrochromic device structureusing a laser patterning/scribing technique. The present inventorsrecognize that reducing and/or minimizing the use of physical masksgreatly benefits the manufacturing process for electrochromic devices,particularly for high-volume manufacturing and large substrates. Some ofthe key benefits of laser patterning are: the positive impact on yield;and the laser allows flexibility in device patterning to accommodateend-market defined form factors, without having to create new expensivephysical masks or reticles. Laser patterning techniques, also referredto as laser scribing, are well known in the semiconductor andphotovoltaic industries. The present invention envisages the use oflasers to directly remove material (ablate material) to create patternedcomponent layers in the electrochromic devices. The lasers are carefullyoptimized and focused, so as to provide accurate edge placement for thefeatures patterned and to allow for removal of one layer while leavingan underlying layer intact. Since electrochromic devices are fabricatedon transparent substrates the lasers can be directed either through thesubstrate or from the top in order to pattern the component layers. Inthe case of large area substrates, and in order to reduce patterningprocess times, multiple lasers can be used at once to pattern devices ona single substrate. Furthermore, as described herein, techniques areemployed for minimizing redeposition of material during laser ablationonto the exposed edges of the active layers of the electrochromicdevice. These same approaches can be used to minimize particulatedeposition from ablated material over all of the surfaces of the device.

Various types of lasers can be used to perform the laserpatterning/scribing function depending on the optical absorptioncharacteristics of the materials used for the electrochromic device andtheir thicknesses. Some of the lasers that can be employed include highpower CO2 lasers (e.g. 10 micron wavelength) and Nd-doped solid statelasers (e.g. Nd:YAG at 1046 nm, and 523 nm with a frequency doubler).Multiple lasers may be used to perform the laser patterning/scribingfunction, including lasers with different wavelengths. The depth of theablation (the number of layers in the device stack that are removed) iscontrolled by the laser power, focus and scanning speed. Furthermore,specificity of the layer to be ablated can be achieved by using aspecific laser wavelength that affects only the desired layer. The laserpatterning/scribing is typically conducted in an inert gas environment,or under vacuum. Debris and gases generated during ablation of thedevice layers may be removed using vacuum/suction in close proximity tothe ablation site. Furthermore, debris and gases may be removed from thevicinity of the electrochromic device by applying a jet of inert gasacross the surface of the device in the region where laser ablation istaking place. Yet further, a (cooled) surface can be strategicallyplaced near the focal point of the ablating region (e.g., where thesuction or gas jet is placed) to capture (via deposition) the ablatedmaterials. The (cooled) surface may be that of a plate made of metal, orother materials, or of any object that is suitable for use in the laserablation environment for capturing ablated material (via deposition).Generally, the ablated materials are not volatile and will readilydeposit on surfaces at room temperature. Those skilled in the art oflaser patterning/scribing will be familiar with the choice of lasers forpatterning/scribing applications, and setting-up laser tools toimplement patterning/scribing processes.

FIGS. 2A to 2E show a first embodiment of a method for manufacturing anelectrochromic device 200 according to the invention. FIG. 2A shows astack of five layers which have been deposited on the substrate 210. Thesubstrate may be glass or plastic. The layers, in order from thesubstrate, are lower transparent conductive oxide (TCO) layer 220, acathode 230, a solid electrolyte 240, a counter electrode 250, and anupper TCO layer 260. The layers are deposited one after another usingdeposition techniques known to those skilled in the art. The lower andupper TCO layers 220 and 260 are typical sputter-deposited indium tinoxide (ITO). The cathode 230 and counter electrode are typically made oftransition metal oxides and are typically deposited by physical vapordeposition methods. The solid electrolyte 240 is typically made ofceramic/oxide solid electrolytes such as lithium phosphorus oxynitrideand LixSiO2, that can be deposited using various methods includingphysical and chemical vapor deposition methods. FIG. 2B shows the stackafter the first patterning step. This patterning step: (1) electricallyisolates individual devices by cutting through the entire stack down tothe substrate; and (2) exposes the top surface of the lower TCO layer220 to allow for making electrical contact to the lower TCO layer 220.The first patterning is preferably implemented by a laser patterningtool. FIG. 2C shows the addition of diffusion barrier layer 270,covering the entire stack including the exposed vertical edges. Thediffusion barrier layer 270 should be transparent, electricallyinsulating, and be capable of passivating the exposed surfaces, with lowpermeability to ambient oxidants, like O2 and H2O. FIG. 2D shows thedevice after the diffusion barrier 270 has been patterned to open upareas 272 and 274 for making electrical contact, respectively, to thelower and upper TCO layers 220 and 260. The second patterning ispreferably implemented by a laser patterning tool. Finally, FIG. 2Eshows the device after making a first electrical contact 280 (to thelower TCO layer 220), and a second electrical contact 290 (to the upperTCO layer 260). Optionally, a diffusion barrier layer may be addedbetween the substrate 210 and the lower TCO layer 220. (Not shown inFIG. 2.) This diffusion barrier layer should be transparent,electrically insulating, and be capable of passivating the exposedsurfaces, with low permeability to ions such as Na, B and Li (in thecase of Li electrochromic devices).

In a second embodiment of the method for manufacturing an electrochromicdevice according to the invention, the method according to FIGS. 2Athrough 2C is followed, then the electrical contacts are made throughthe barrier layer 270, without the need to open up contact areas 272 and274 in the barrier layer 270. This method of making contact works bydiffusing the contact material through the diffusion barrier layer tomake an electrically conductive path. This results in the same finaldevice as shown in FIG. 2E, except the first and second electricalcontacts 280 and 290 sit on the diffusion barrier layer 270 and makeelectrical contact to the lower and upper TCO layers 220 and 260,respectively, through the diffusion barrier layer 270 (made locallyconductive by contact material diffused into the diffusion barrierlayer). This method is applicable when the diffusion barrier layer iseither very thin or relatively porous. This may be the case when thedemands on the diffusion barrier layer are less stringent due to thepresence of an alternative method for protecting the electrochromicdevices from ambient oxidants. For example, the electrochromic devicesmight be incorporated into low-e insulating glass units (IGUs) which aresealed with an inert gas within.

The first embodiment of a method of the invention, described above withreference to FIGS. 2A-2E, includes a first patterning step which cutsthrough all five layers of the stack. When laser patterning/scribing isused to implement this patterning step there may be some risk ofredeposition of ablated material onto the newly exposed edges of thestack. This redeposition may result in shorting between layers orcontamination of the active layers. If redeposition is a problem thereare alternative methods of the invention that can be used whichspatially separate the edges and minimize redeposition by patterningsome of the lower conductive layers prior to depositing and patterningthe upper layers. These methods include the addition of one or morepatterning steps. An example of such a method is the embodiment shown inFIGS. 3A to 3E where the edges of the cathode 330 are spatiallyseparated from the edges of the layers in the stack above it and thecathode 330 and lower transparent conductive oxide layer 320 arepatterned prior to deposition and patterning of the upper layers.

FIGS. 3A to 3E show a third embodiment of a method for manufacturing anelectrochromic device 300 according to the invention. FIG. 3A shows astack of two layers which have been deposited on the substrate 310. Thelayers, in order from the substrate, are lower transparent conductiveoxide (TCO) layer 320, and a cathode 330. The layers are deposited oneafter another using deposition techniques known to those skilled in theart. FIG. 3B shows the stack after the first patterning step. Thispatterning step: (1) electrically isolates individual devices by cuttingthrough the stack down to the substrate; and (2) exposes the top surfaceof the lower TCO layer 320 to allow for making electrical contact to thelower TCO layer 320. The first patterning is preferably implemented by alaser patterning tool. FIG. 3C shows the addition of another threelayers: a solid electrolyte 340, a counter electrode 350, and an upperTCO layer 360. The layers are deposited one after another usingdeposition techniques known to those skilled in the art. FIG. 3D showsthe stack after the second patterning step. This patterning step: (1)electrically isolates the counter electrode 350 and upper TCO layer 360;and (2) exposes the top surface of the lower TCO layer 320 again toallow for making electrical contact to the lower TCO layer 320. Thesecond patterning is preferably implemented by a laser patterning tool.FIG. 3E shows the addition of diffusion barrier layer 370, covering theentire stack including the exposed vertical edges. The process nowproceeds as in either the first embodiment of the method, as shown inFIGS. 2A-2E, or the second embodiment described above.

FIG. 4 shows a stack 400 with substrate 410 and layers 420-470,equivalent to layers 120-170 described above. The stack 400 is subjectto laser patterning/scribing by a laser 401 focused on the stack throughthe substrate 410 and a laser 402 focused on the stack from above. Thelaser 401 was originally focused on layer 470 and as the layer ablatedthe laser focus was moved down to layer 460 and then to layer 450 (shownin FIG. 4), forming a hole 405. As the laser ablates the layers of thestack 400, debris 403 is produced. Tube 406 (shown in cross-section) isconnected to a vacuum pump/suction generator and is shown removingdebris 403 along the tube 406 in direction 404. Depending on the patternrequired, the number of layers to be removed, and the optical propertiesof the component layers, the laser may be scanned to remove materiallayer by layer (requiring repeated scanning of the same patternarea—once for each layer to be removed) or may be scanned across thepattern area once, cutting through multiple layers. The laser 402 wasoriginally focused on layer 470 and as the layer ablated the laser focuswas moved down to layer 460 and then to layer 450 (shown in FIG. 4),forming a hole 405. As the laser ablates the layers of the stack 400debris 403 is produced. Tube 407 (shown in cross-section) is connectedto a vacuum pump/suction generator and is shown removing debris 403along the tube 407 in direction 404. The laser beam 402 is showntraveling through the tube 407; however, the tube may be placed to oneside of the laser beam if desired. The laser beam 402 is scanned asdescribed above for laser beam 401.

FIG. 5 shows a stack 500 with substrate 510 and layers 520-570,equivalent to layers 120-170 described above. The stack 500 is subjectto laser patterning/scribing by a laser 501 focused on the stack throughthe substrate 510 and a laser 502 focused on the stack from above, bothlasers being focused simultaneously on the same general area. Togetherthe lasers have ablated material to form hole 505. The laser 502 isshown focused on layer 550 and laser 501 is shown focused on layer 540.As the lasers ablate the layers of the stack 500, debris 503 and bubbles599, of vaporized material, are produced. Tubes 509 and 508 (shown incross-section) together form an annular space through which debris 503is removed in direction 504. (The annular space is connected to a vacuumpump/suction generator.) The laser beam 502 is shown traveling throughthe middle of tube 508; however, tubes as shown in FIG. 4 may be usedinstead of tubes 508 and 509. The laser beams 501 and 502 are scanned asdescribed above for laser beam 401.

FIG. 6 shows a stack 600 with substrate 610 and layers 620-670,equivalent to layers 120-170 described above. The stack 600 is subjectto laser patterning/scribing by a laser 602 focused on the stack fromabove. The laser 602 was originally focused on layer 670 and as thelayer ablated the laser focus was moved down to layer 660 and then tolayer 650 (shown in FIG. 6), forming a hole 605. As the laser ablatesthe layers of the stack 600, debris 603 and bubbles 699, of vaporizedmaterial, are produced. Tube 695 (shown in cross-section) is connectedto a supply of inert gas, such as argon, and delivers a jet of inert gasonto the surface of the stack 600, in the direction 696. The jet ofinert gas blows the debris 603 away from the site of laser ablationacross the surface of the wafer. Here the debris is shown beingcollected by a suction tube 606. However, a jet of inert gas alone canbe effective in removing debris away from the site of laser ablation andoff the surface of the stack 600. Tube 606 (shown in cross-section) isconnected to a vacuum pump/suction generator and is shown removingdebris 603 along the tube 606 in direction 604. The laser beam 602 isscanned as described above for laser beam 401.

Although the present invention has been particularly described withreference to the preferred embodiments thereof, it should be readilyapparent to those of ordinary skill in the art that changes andmodifications in the form and details may be made without departing fromthe spirit and scope of the invention. It is intended that the appendedclaims encompass such changes and modifications.

What is claimed is:
 1. An electrochromic device comprising: atransparent substrate; a first transparent conductive layer on saidtransparent substrate; a cathode layer on said first transparentconductive layer, said cathode layer being patterned to not cover afirst area of said first transparent conductive layer; a solidelectrolyte layer on said cathode layer, said solid electrolyte layercompletely covering the top surface of said cathode layer and the edgesof said cathode layer; a counter electrode layer on said electrolytelayer; a second transparent conductive layer on said counter electrodelayer; and a diffusion barrier layer over said second transparentconductive layer.
 2. The electrochromic device of claim 1, wherein saidsolid electrolyte layer, said counter electrode layer and said secondtransparent conductive layer are a co-extensive stack.
 3. Theelectrochromic device of claim 2, wherein said co-extensive stack doesnot cover a second area of said first transparent conductive layer andsaid diffusion barrier layer covers said second area.
 4. Theelectrochromic device of claim 2, wherein said diffusion barrier layercovers the entire co-extensive stack, including edges of saidco-extensive stack.
 5. The electrochromic device of claim 1, whereinsaid diffusion barrier layer includes a first aperture over said firsttransparent conductive layer and a second aperture over said secondtransparent conductive layer.
 6. The electrochromic device of claim 5,further comprising a first electrical contact to said first transparentconductive layer through said first aperture and a second electricalcontact to said second transparent conductive layer through said secondaperture.
 7. The electrochromic device of claim 1, further comprising afirst electrical contact to said first transparent conductive layer onsaid diffusion barrier layer and a second electrical contact to saidsecond transparent conductive layer on said diffusion barrier layer,wherein said first and second electrical contacts are diffused throughsaid diffusion barrier layer.
 8. The electrochromic device of claim 1,wherein said first transparent conductive layer and said cathode layerare patterned to not cover areas of said substrate.
 9. Theelectrochromic device of claim 8, wherein, peripheral to said cathodelayer, said solid electrolyte layer is on a portion of said firsttransparent conductive layer and a portion of said substrate.
 10. Theelectrochromic device of claim 1, wherein said first transparentconductive layer comprises sputter deposited indium tin oxide.
 11. Theelectrochromic device of claim 1, wherein said second transparentconductive layer comprises sputter deposited indium tin oxide.
 12. Theelectrochromic device of claim 1, wherein said cathode layer comprisestransition metal oxide.
 13. The electrochromic device of claim 1,wherein said counter electrode layer comprises transition metal oxide.14. The electrochromic device of claim 1, wherein said solid electrolytelayer comprises lithium phosphorus oxynitride.
 15. The electrochromicdevice of claim 1, wherein said diffusion barrier layer is transparent,electrically insulating and protects the underlying layers from ambientoxidants.
 16. The electrochromic device of claim 14, wherein saiddiffusion barrier layer passivates the surfaces of said underlyinglayers that are in physical contact with said diffusion barrier layer.